JP2007-48479A, published by the Japan Patent Office in 2007, discloses an operation control device for a fuel cell power plant which performs a pressure pulsation operation on an anode gas. A pressure pulsation operation is an operation method in which an internal pressure of a fuel cell stack is caused to pulsate between an upper limit pressure and a lower limit pressure by halting an anode gas supply to the fuel cell stack when a pressure of the anode gas reaches the upper limit pressure and restarting the anode gas supply when the pressure of the anode gas falls to the lower limit pressure. With this prior art technique, it is possible to promote the discharge of water generated in the fuel cell stack along a pressure gradient formed as the pressure falls during the pressure pulsation operation.